Numerous systems have been employed to attach rotor blades to the hub of a helicopter. These systems generally incorporate grips. The grips couple the rotor blade to the yoke. The directional and thrust control, such as pitch, of the blades is controlled through the grips. In the past, grips have been made from metals such as steel and aluminum. These metals are heavy, and weight is a design parameter that must be kept at a minimum in aircraft applications. Therefore, a need for a lightweight grip made from composite materials exists.
In many applications, it is desirable that the grips transfer the centrifugal forces (hereinafter CF) exerted by the rotation of a blade in flight to the yoke; placing the yoke in tension reducing bending stress by making the yoke a tension loading beam. Therefore, it is desirable to provide blade attachment systems that provide redundant load paths for transferring the CF from the blade to the yoke while reducing vibrations and meeting the design criteria for strength and stiffness.